I saved my game, and then went out to Main Menu. When I came back in on my saved game, stuck horn was gone and I was able to use the horn...
I had the same thing happen on Sand Patch Grade with the ac4400cw loco but ONLY in bad weather conditions (rain).
One you switch from Immersive to Classic view, push down the right stick to access camera views. Then click on Internal Camera. Above the list...
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